The promotion is live from 10 a.m. to 2 p.m. local time, giving people a chance to try the coffee, which the chain says is “crafted by hand in small batches, prepared by steeping a special blend of coffee in cold water for 12 hours.”

With that kind of preparation time, it’s no surprise that this is a “while supplies last” kind of promotion.

Cold brew coffee is a trend that’s taken off over the last few years. As opposed to iced coffee, where espresso is cooled with ice and generally mixed with other things like milk and syrup, cold brew coffee uses a whole different brewing process.

The lengthy process supposedly brings out different characteristics of the grounds, compared with traditional hot brewing techniques. Cold brew coffee is supposed to be smoother and less bitter, with more of a floral profile. Due to that lack of bitterness, it’s easier to drink black and sugar-free.

Dunkin’ Donuts has been offering cold brew coffee since August 2016, but with the seasons changing, it’s clearly decided that now is a good time to remind people about it.